OMG Nikhil pawned…
Game companies build game engines thats built on directx/opengl. This game engine has all the routines and functions thats required for coding the game at a fast pace…It also makes programming easy…
say you want to retrieve the obj world position, you dont then need to code shit…just say obj.position n bingo u get the vectors…even the shader n lighting info becomes easy using the popular game engines…
Everythings not quite as simple but then this is one way of looking at it…